1. Field of the Invention
The present invention generally relates to a method for manufacturing a wooden golf head and, more particularly, to a method for manufacturing a low-density steel golf head with a reduced thickness.
2. Description of the Related Art
Early wooden golf heads are made of stainless or carbon steel. In order to increase the performance of the wooden golf heads, several new steel-type casting materials have been continuously developed in recent years and have been used to manufacture wooden golf heads. For example, steel-type alloys containing aluminum (Al), silicon (Si), or manganese (Mn) generally have a low density below 7.6 g/cm3. Therefore, such steel-type alloys are suitable for manufacturing the wooden golf heads, which decrease the total weight of the wooden golf heads and improve the hitting effect of the wooden golf heads.
Current wooden golf heads are manufactured by using a high frequency induction furnace to rapidly melt the casting materials in the atmosphere, followed by removing the slag and gases in the molten metal by slagging and refinery. Static gravity pouring is then carried out. However, the casting materials for the low-density wooden golf heads include active metals, such as aluminum or manganese that are apt to react with oxygen in the air. Thus, rigorous oxidation easily occurs during the procedures of smelting of the casting materials, increasing difficulties in melting and easily causing oxidative fire cracks due to reaction with air during the pouring process. As a result, appearance defects, such as sesame dot defects and black bean defects, are apt to be formed on the cast products of the wooden golf heads. In worse situations, the reactive gas forms a large number of slag holes or blowholes in the cast products of the wooden golf heads and, thus, adversely affects the tensile strength of the wooden golf heads.
Furthermore, rigorous oxidation also reduces the flowability of the molten metal in the shell mold, leading to a reduced yield rate of the cast products of the wooden golf heads due to insufficient pouring or resulting in gaps in the cast products of the wooden golf heads due to cold shut. The tensile strength of the cast products of the wooden golf heads is also adversely affected.
Therefore, the thickness of the wooden golf heads manufactured by static gravity pouring in the atmosphere should be thick enough to improve the yield rate, and the forced shaping cast products are easily destroyed due to the inadequate structural strength. That is to say, the average thickness of the entire integrally shaped wooden golf heads is relatively thick, and therefore, the wooden golf heads manufactured with low-density casting materials still have a relative high weight.
On the other hand, on the wooden golf heads manufactured by static gravity pouring, additional casting materials are needed to elevate the pressing effect of the molten metal and to improve the yield rate of the wooden golf heads. However, the additional casting materials and the energy used for melting the additional casting materials result in the increased manufacturing cost.
In light of this, it is necessary to improve the conventional method for manufacturing a steel golf head.